Knitted tissue scaffolds

ABSTRACT

Staple cartridge assemblies for use with surgical stapling instruments and methods for manufacturing the same are provided. Scaffolds for use with a surgical staple cartridge and methods for manufacturing the same are also provided.

FIELD

Knitted tissue scaffolds and methods for manufacturing the same areprovided.

BACKGROUND

Surgical staplers are used in surgical procedures to close openings intissue, blood vessels, ducts, shunts, or other objects or body partsinvolved in the particular procedure. The openings can be naturallyoccurring, such as passageways in blood vessels or an internal organlike the stomach, or they can be formed by the surgeon during a surgicalprocedure, such as by puncturing tissue or blood vessels to form abypass or an anastomosis, or by cutting tissue during a staplingprocedure.

Some surgical staplers require a surgeon to select the appropriatestaples having the appropriate staple height for the tissue beingstapled. For example, a surgeon could select tall staples for use withthick tissue and short staples for use with thin tissue. In someinstances, however, the tissue being stapled does not have a consistentthickness and, thus, the staples cannot achieve the desired firedconfiguration at each staple site. As a result, a desirable seal at ornear all of the stapled sites cannot be formed, thereby allowing blood,air, gastrointestinal fluids, and other fluids to seep through theunsealed sites.

Further, staples, as well as other objects and materials that can beimplanted in conjunction with procedures like stapling, generally lacksome characteristics of the tissue in which they are implanted. Forexample, staples and other objects and materials can lack the naturalflexibility of the tissue in which they are implanted, and therefore areunable to withstand the varying intra-tissue pressures at theimplantation site. This can lead to undesirable tissue tearing, andconsequently leakage, at or near the staple site, and/or leakage betweenthe apposed implant and tissue.

Accordingly, there remains a need for improved instruments and methodsthat address current issues with surgical staplers.

SUMMARY

Methods for manufacturing scaffolds and staple cartridge assemblies areprovided.

In one exemplary embodiment, the method can include forming a firstknitted layer that can include fibers of a first polymer and can beconfigured to mate with a cartridge deck, forming a second knitted layerthat can include the first polymer fibers, and interknitting spacerfibers with the first and second knitted layers so as to connect thefirst and second knitted layers together in a spaced parallel relation.The spacer fibers can be formed of only a second polymer that isdifferent than the first polymer in which the spacer fibers can beintegrated with and extending between the first and second knittedlayers. The first polymer fibers can have a diameter that is differentthan a diameter of the second polymer fibers. In one aspect, the methodcan also include annealing the first and second knitted layersinterknitted with the spacer fibers.

In some aspects, the first polymer fibers can be multifilament fibersand the second polymer fibers can be monofilament fibers. In otheraspects, the first polymer fibers can be configured to degrade at afirst rate and the second polymer fibers can be configured to degrade ata second rate that is different than the first rate. In yet otheraspects, the first polymer fibers can have a first glass transitiontemperature and the second polymer fibers can have a second glasstransition temperature that is less than the first glass transitiontemperature.

In some aspects, the formation of the first knitted layer can includeknitting the first polymer fibers according to a predetermined pattern.In other aspects, the formation of the second knitted layer can includeknitting the first polymer fibers according to a predetermined pattern.

The first knitted layer can have a variety of configurations. Forexample, in one aspect, the first knitted layer can have openings thateach have a size that is less than about ¼ of a width of a crown of astaple. In another aspect, the first knitted layer can further includefibers of a third polymer, and the formation of the first knitted layercan include knitting the first and third polymer fibers according to apredetermined pattern. In one embodiment, the third polymer fibers canbe configured to degrade at a faster rate than a rate of degradation ofthe first polymer fibers. In another embodiment, the third polymerfibers can be configured to degrade at a faster than a rate ofdegradation of the second polymer fibers.

The second knitted layer can have a variety of configurations. Forexample, in one aspect, the second knitted layer can further includefibers of a third polymer in which the formation of the second knittedlayer can include knitting the first and third polymer fibers accordingto a predetermined pattern.

In some aspects, the step of interknitting the spacer fibers with thefirst and second knitted layers can form a support layer therebetween.In such aspects, openings can be present in the first and second knittedlayers and voids can be present in the support layer, with the voidsbeing larger than the openings.

Methods for manufacturing staple cartridge assemblies are also provided.In one exemplary embodiment, the method can include heating a cartridgedeck, and positioning a knitted elastically deformable, bioabsorbablescaffold against a surface of the cartridge deck, where the scaffold caninclude first and second knitted layers each having fibers of a firsttype and fibers of a second type in which the first type of fibers beingpredominantly present and the first type of fibers have a first glasstransition temperature and the second type of fibers have a second glasstransition temperature that is less than the first glass transitiontemperature, and a support layer disposed between the first and secondknitted layers, the support layer being formed of the second type offibers, where the cartridge deck is heated to a temperature of at leastthe second glass transition temperature. In one aspect, the method ofclaim 13, the first glass transition temperature is greater than thesecond glass transition temperature by at least about 30 degrees C.

In some aspects, the method can also include cooling the cartridge deckand scaffold applied thereto to a temperature that is less than thesecond glass transition temperature. In other aspects, the positioningof the scaffold against the surface of the cartridge deck can includeplacing the first knitted layer against the surface and applying forceto the scaffold such that the first knitted layer bonds and conforms toa shape of the surface.

The cartridge deck can have a variety of configurations. For example, inone aspect, the cartridge deck can include a plurality of staples witheach staple partially extending from the surface of the cartridge deck.In another aspect, the surface of the cartridge deck can include one ormore attachment features that can be configured to enhance attachment ofthe scaffold to the cartridge deck.

Staple cartridge assemblies for use with a surgical stapling instrumentand scaffolds for use with a surgical staple cartridge are alsoprovided.

In one exemplary embodiment, a staple cartridge assembly is provided andcan include a staple cartridge having a plurality of staples and acartridge deck, and a knitted elastically deformable, bioabsorbablescaffold formed of at least two different fiber materials and havingattachment properties such that the scaffold is configured to mate withthe cartridge deck, where the staples are deployable through thescaffold into tissue captured against the scaffold. The scaffold caninclude first and second knitted layers and a support layer disposedbetween the first and second knitted layers. The first and secondknitted layers can each include fibers of a first type and fibers of asecond type, where the first type of fibers are predominantly present.The first type of fibers can have a first glass transition temperatureand the second type of fibers can have a second glass transitiontemperature that is less than the first glass transition temperature.The support layer can be formed of the second type of fibers. In oneaspect, the first glass transition temperature can be greater than thesecond glass transition temperature by at least about 30 degrees C. Inanother aspect, an outer surface of the cartridge deck can include oneor more attachment features that are configured to engage the scaffold.

In some aspects, the second type of fibers can interconnect with thefirst type of fibers of the first and second knitted layers in a mannersuch that the first and second fibers are non-fixedly attached.

In some aspects, the first type of fibers can be multifilament fibersand the second type of fibers can be monofilament fibers. In one aspect,the first type of fibers can be coated with a bioabsorbable polymericmaterial.

The first and second type of fibers can be formed of a variety ofmaterials. In one aspect, the first type of fibers can be formed of atleast one of poly-L-lactic acid, a copolymer of glycolide and L-lactide,a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide. In another aspect,the second type of fibers can be formed of at least one ofpolydioxanone, a copolymer of polydioxanone and polyglycolide, acopolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

The scaffold can also have a variety of configurations. For example, inone aspect, the scaffold can be configured to be thermoformed to thecartridge deck, where the second knitted layer abuts the cartridge deck.In another aspect, the scaffold can be configured to apply a stress ofat least about 3 g/mm² to the captured tissue for at least 3 days whenthe scaffold is in a tissue deployed state. In yet another aspect, thescaffold can be configured to deform from an non-deformed height to adeformed height, where the non-deformed height is greater than a heightof each staple of the plurality of staples when the staple is in aformed configuration.

In another exemplary embodiment, a staple cartridge assembly is providedand can include a staple cartridge having a plurality of staples and acartridge deck, and a knitted elastically deformable, bioabsorbablescaffold, where the staples are deployable through the scaffold intotissue captured against the scaffold. The scaffold can include at leasttwo layers. The first layer can be knitted and can include first andsecond fibers and the second layer includes only the second fibers. Thefirst and second fibers can be formed of different materials and thefirst fibers can have a glass transition temperature that is greaterthan a glass transition temperature of the second fibers. The secondfibers in the second layer can be knitted into the first knitted layerin a manner such that the second fibers form supporting members that areoriented substantially perpendicular to the first fibers in the firstlayer. In one aspect, the glass transition temperature of the firstfibers can be greater than the glass transition temperature of thesecond fibers by at least about 30 degrees C. In another aspect, thefirst fibers can be coated with a bioabsorbable polymeric material.

In some aspects, the scaffold can also include a third layer that caninclude the first and second fibers, where the third layer can beknitted and the second layer can be positioned between the first andthird layers.

In one aspect, the second fibers can interconnect with the first fibersin a manner such that the first and second fibers are non-fixedlyattached.

The scaffold can also have a variety of configurations. For example, inone aspect, the scaffold can be configured to be thermoformed to thestaple cartridge, where the second knitted layer abuts the cartridgedeck. In another aspect, the scaffold can be configured to apply astress of at least about 3 g/mm² to the captured tissue for at least 3days when the scaffold is in a tissue deployed state. In yet anotheraspect, the scaffold can be configured to deform from an undeformedheight to a deformed height, where the undeformed height greater is thana height of each staple of the plurality of staples when the staple isin a formed configuration.

In some aspects, an outer surface of the cartridge deck can include oneor more attachment features that are configured to engage the knittedscaffold.

In one exemplary embodiment, a scaffold is provided and can includefirst and second knitted layers each having fibers of a first type andfibers of a second type, where the first type of fibers beingpredominantly present, and a support layer disposed between the firstand second knitted layers, where the support layer being formed of thesecond type of fibers. The first type of fibers can have a first glasstransition temperature and the second type of fibers can have a secondglass transition temperature that is less than the first glasstransition temperature.

In one exemplary embodiment, a staple cartridge assembly is provided andcan include staple cartridge having a plurality of staples and acartridge deck, and a knitted bioabsorbable scaffold in which thestaples are deployable through the scaffold into tissue captured againstthe scaffold. The scaffold can include a first knitted layer that can beconfigured to be positioned against tissue, a second knitted layer thatcan be configured to be positioned against the cartridge deck, and asupport layer disposed between the first and second layers. The firstknitted layer can have a plurality of openings formed therein and can beformed of fibers formed of a first bioabsorbable polymer. The secondknitted layer can have a plurality of openings formed therein and can beformed of the fibers formed of the first bioabsorbable polymer, wherethe openings can have a size that is less than about ¼ of a width of acrown of the staples. The support layer can be formed of a fiber of asecond bioabsorbable polymer. The fiber of the support layer canarranged to form standing fibers and a plurality of voids therebetween,where the standing fibers can be not fixedly attached to each other, andwhere a ratio of the voids to the second absorbable polymer within thesupport layer can be in the range of at least about 3:1. In one aspect,the scaffold can be configured to apply a stress of at least about 3g/mm² to the captured tissue for at least 3 days when the scaffold is ina tissue deployed state.

In one aspect, at least one of the first knitted layer and the secondknitted layer can further include fibers formed of a third bioabsorbablepolymer. In another aspect, the fibers of the support layer can beconnected to the first and second knitted layers, such that the fibersare slidably interconnected with the fibers of the first and secondknitted layers.

In some aspects, each opening of the plurality of openings in the firstand second knitted layers can have a perimeter formed of the first andsecond bioabsorbable polymers. In another aspects, each opening of theplurality of openings formed in the second knitted layer can beconfigured to have a diameter from about 0.002 inches to 0.1 inches.

In one aspect, at least a portion of the voids in the support layer eachcan have a different size. In another aspect, the standing fibers can beoriented substantially perpendicular to the fibers of the firstbioabsorbable polymer in the first and second knitted layers.

In another exemplary embodiment, a staple cartridge assembly is providedand can include a staple cartridge having a plurality of staples and acartridge deck, and a knitted bioabsorbable scaffold in which thestaples are deployable through the scaffold into tissue captured againstthe scaffold. The scaffold can include a first knitted layer that can beconfigured to be positioned against tissue, a second knitted layer thatcan be configured to be positioned against the cartridge deck, and asupport layer. The first knitted layer can have a plurality of openingsformed therein, and can be formed of multifilament fibers formed of afirst bioabsorbable polymer and monofilament fibers formed of a secondbioabsorbable polymer. The second knitted layer can have a plurality ofopenings formed therein and can be formed of the multifilament andmonofilament fibers, where the openings can have a size that is lessthan about ¼ of a width of a crown of the staples. The support layer canhave spacer fibers extending from the first knitted layer to the secondknitted layer and a plurality of voids therebetween in which each spacerfiber can be formed of the monofilament fibers and ends of the spacerfibers can be slidably intertwined with the first and second knittedlayers, where a ratio of the voids to the spacer fibers within thesupport layer can be in the range of at least about 3:1. In one aspect,the scaffold can be configured to apply a stress of at least about 3g/mm² to the captured tissue for at least 3 days when the scaffold is ina tissue deployed state.

In some aspects, each opening of the plurality of openings in the firstand second knitted layers can have a perimeter formed of themultifilament and monofilament fibers. In other aspects, each opening ofthe plurality of openings formed in the second knitted layer can beconfigured to have a diameter from about 0.002 inches to 0.1 inches.

In one aspect, at least a portion of the voids in the support layer eachhave a different size. In another aspects, the spacer fibers can beoriented substantially perpendicular to the multifilament fibers of thefirst and second knitted layers.

In one exemplary embodiment, a scaffold is provided and can include afirst knitted layer configured to be positioned against tissue, a secondknitted layer configured to be positioned against a cartridge deck, anda support layer disposed between the first and second layers. The firstknitted layer can have a plurality of openings formed therein and can beformed of fibers formed of a first bioabsorbable polymer. The secondknitted layer can have a plurality of openings formed therein and can beformed of the fibers formed of the first bioabsorbable polymer, wherethe openings have a size that is less than about ¼ of a width of a crownof a staple within the cartridge deck. The support layer can be formedof a fiber of a second bioabsorbable polymer in which the fiber of thesupport layer is arranged to form standing fibers and a plurality ofvoids therebetween, where the standing fibers can be not fixedlyattached to each other, and where a ratio of the voids to the secondabsorbable polymer within the support layer can be in the range of atleast about 3:1.

In one exemplary embodiment, a staple cartridge assembly is provided andcan include a staple cartridge having a plurality of staples and acartridge deck, and a knitted elastically deformable, bioabsorbablescaffold attached to the cartridge deck and formed of at least threedistinct zones, each having a different functionality, where the staplesare deployable through the scaffold into tissue captured against thescaffold. The scaffold can include a first knitted zone that can beconfigured to promote tissue ingrowth, a second knitted zone that can beconfigured to be conformable so as to attach to the cartridge deck, anda spacer zone that is disposed between the first and second knittedzones and can be configured to support the first and second knittedzones, where openings are present in the first and second knitted zonesand voids are present in the spacer zone, with the voids being largerthan the openings. The first knitted zone can include first fibers madeof a first bioabsorbable polymer and second fibers made of a secondbioabsorbable polymer, where each first fiber has a fiber diameter thatis less than a fiber diameter of each second fiber. The second knittedzone can include the first and second fibers of the first knitted zone.The spacer zone can be formed of the second fibers in which the secondfibers are non-fixedly and slidably interconnected to the first fibersof the first and second knitted zones. In one aspect, the scaffold canbe configured to apply a stress of at least about 3 g/mm² to thecaptured tissue for at least 3 days when the scaffold is in a tissuedeployed state.

In some aspects, the fiber diameters of the first fibers can be fromabout ⅕ to 1/20 of the fiber diameters of the second fibers. In otheraspects, the fiber diameters of the first fibers can be about 1/10 ofthe fiber diameters of the second fibers.

In one aspect, the second fibers can extend from the first knitted zoneto the second knitted zone such that the second fibers extend across thespacer zone and at least a portion of the second fibers within thespacer zone can be oriented substantially perpendicular to the firstfibers of the first and second knitted zones.

The first and second type of fibers can be formed of a variety ofmaterials. In one aspect, the first type of fibers can be formed of atleast one of poly-L-lactic acid, a copolymer of glycolide and L-lactide,a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide. In another aspect,the second type of fibers can be formed of at least one ofpolydioxanone, a copolymer of polydioxanone and polyglycolide, acopolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In another exemplary embodiment, a staple cartridge assembly is providedand can include a staple cartridge having a plurality of staples and acartridge deck, and a knitted elastically deformable, bioabsorbablescaffold attached to the cartridge deck and formed of at least threedistinct zones, each having a different functionality, where the staplesare deployable through the scaffold into tissue captured against thescaffold. The scaffold can include a first zone that can have a knittedconfiguration and that can be configured to promote tissue ingrowth,where the first zone includes first fibers made of a first bioabsorbablepolymer. The scaffold can also include a second zone that can be formedof second fibers made of a second bioabsorbable polymer and that can beconfigured to vertically support the first zone, where the second fibersare non-fixedly and slidably interconnected to the first fibers of thefirst zone such that the second fibers are substantially verticallyoriented within the second zone. Each first fiber can have a fiberdiameter that is less than a fiber diameter of each second fiber, andwherein openings are present in the first zone and voids are present inthe second zone, with the voids being larger than the openings.

In some aspects, the scaffold can also include a third zone that canhave a knitted configuration and that can be configured to beconformable so as to attach to the cartridge deck, where the third zonecan include the first fibers and the second zone can be located betweenthe first and third zones. In such instances, the second fibers can benon-fixedly and slidably interconnected to the first fibers of the thirdzone in which the second fibers can extend from the first zone to thethird zone such that at least a portion of the second fibers arevertically oriented within the second zone. The scaffold can beconfigured to apply a stress of at least about 3 g/mm² to the capturedtissue for at least 3 days when the scaffold is in a tissue deployedstate.

In some aspects, the fiber diameters of the first fibers can be fromabout ⅕ to 1/20 of the fiber diameters of the second fibers. In otheraspects, the fiber diameters of the first fibers can be about 1/10 ofthe fiber diameters of the second fibers.

The first and second type of fibers can be formed of a variety ofmaterials. In one aspect, the first type of fibers can be formed of atleast one of poly-L-lactic acid, a copolymer of glycolide and L-lactide,a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide. In another aspect,the second type of fibers can be formed of at least one ofpolydioxanone, a copolymer of polydioxanone and polyglycolide, acopolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In one exemplary embodiment, a scaffold is provided and can include afirst knitted zone that is configured to promote tissue ingrowth, asecond knitted zone that is configured to be conformable so as to attachto a cartridge deck, and a spacer zone that is disposed between thefirst and second knitted zones and is configured to support the firstand second knitted zones, where openings are present in the first andsecond knitted zones and voids are present in the spacer zone, with thevoids being larger than the openings. The first knitted zone can includefirst fibers made of a first bioabsorbable polymer and second fibersmade of a second bioabsorbable polymer, where each first fiber has afiber diameter that is less than a fiber diameter of each second fiber.The second knitted zone can include the first and second fibers of thefirst knitted zone. The spacer zone can be formed of the second fibers,where the second fibers can be non-fixedly and slidably interconnectedto the first fibers of the first and second knitted zones.

In one exemplary embodiment, a staple cartridge assembly is provided caninclude a staple cartridge having a plurality of staples and a cartridgedeck, and a knitted elastically deformable, bioabsorbable scaffoldformed of at least two different fiber materials, where the staples aredeployable through the scaffold into tissue captured against thescaffold and the scaffold is a multi-layered construct. Themulti-layered construct can include a first layer that can havemultifilament fibers, with at least a portion of the multifilamentfibers being oriented in a direction that is substantially parallel tothe cartridge deck, and a second layer that can be formed ofmonofilament fibers that are oriented in a direction that issubstantially non-parallel to the cartridge deck in which themonofilament fibers can have a diameter that is less than an averagediameter of the multifilament fibers. In one aspect, the monofilamentfibers can be non-fixedly and slidably interconnected to themultifilament fibers of the first layer.

In some aspects, the multifilament fibers can be non-bondedmultifilament fibers. In another aspect, the multifilament fibers can benot present within the second layer.

In some aspects, the multi-layered construct can also include a thirdlayer that can have the multifilament fibers, with at least a portion ofthe multifilament fibers being oriented in a direction that issubstantially parallel to the cartridge deck. The second layer can bepositioned between the first and third layers. In one aspect, themonofilament fibers can be non-fixedly and slidably interconnected tothe first fibers of the first layer and third layers. In another aspect,the scaffold can be configured to apply a stress of at least about 3g/mm² to the captured tissue for at least 3 days when the scaffold is ina tissue deployed state.

The multifilament and monofilament fibers can be formed of a variety ofmaterials. In one aspect, the multifilament fibers can be formed of atleast one of poly-L-lactic acid, a copolymer of glycolide and L-lactide,a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide. In another aspect,the monofilament fibers can be formed of at least one of polydioxanone,a copolymer of polydioxanone and polyglycolide, a copolymer of Lactideand polycaprolactone), a copolymer of glycolide, dioxanone, andtrimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In another exemplary embodiment, a surgical cartridge assembly isprovided and can include a staple cartridge having a plurality ofstaples and a cartridge deck, and a knitted elastically deformable,bioabsorbable scaffold formed of at least two different fiber materials,where the staples are deployable through the scaffold into tissuecaptured against the scaffold and the scaffold is a multi-layeredconstruct. The multi-layered construct can include first and secondlayers each having multifilament fibers, with at least a portion of themultifilament fibers being oriented in a direction that is substantiallyparallel to the cartridge deck, and an intermediate layer positionedbetween the first and second layers and can be formed of onlymonofilament fibers that are oriented in a direction that issubstantially non-parallel to the cartridge deck. The monofilamentfibers can have a diameter that is less than an average diameter of themultifilament fibers. In one aspect, the monofilament fibers can benon-fixedly and slidably interconnected to the multifilament fibers ofthe first and second layers. In another aspect, each of themultifilament fibers can be non-bonded multifilament fibers.

In some aspects, the scaffold can be configured apply a stress of atleast about 3 g/mm² to the captured tissue for at least 3 days when thescaffold is in a tissue deployed state.

The multifilament and monofilament fibers can be formed of a variety ofmaterials. In one aspect, the multifilament fibers can be formed of atleast one of poly-L-lactic acid, a copolymer of glycolide and L-lactide,a copolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide. In another aspect,the monofilament fibers can be formed of at least one of polydioxanone,a copolymer of polydioxanone and polyglycolide, a copolymer of Lactideand polycaprolactone), a copolymer of glycolide, dioxanone, andtrimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In one exemplary embodiment, a scaffold is provided and can include afirst layer that can be configured to mate to a cartridge deck, and asecond layer. The first layer can have multifilament fibers, with atleast a portion of the multifilament fibers configured to be oriented ina direction that is substantially parallel to the cartridge deck. Thesecond layer can be formed of monofilament fibers that are configured tobe oriented in a direction that is substantially non-parallel to thecartridge deck. The monofilament fibers can have a diameter that is lessthan an average diameter of the multifilament fibers.

In some aspects, the scaffold can also include a third layer that canhave the multifilament fibers, with at least a portion of themultifilament fibers configured to be oriented in a direction that issubstantially parallel to the cartridge deck. The second layer can bepositioned between the first and third layers.

In one exemplary embodiment, a staple cartridge assembly is provided andcan include a staple cartridge having a plurality of staples and acartridge deck, a knitted elastically deformable, bioabsorbablecomposite scaffold formed of a plurality of fiber materials, where thescaffold is configured to mate with the cartridge deck and the staplesare deployable through the scaffold into tissue captured against thescaffold. The scaffold can include a tissue interaction surface and acartridge deck interaction surface, and an intermediate layer that canbe disposed between the tissue interaction surface and the cartridgedeck interaction surface. The tissue interaction surface and thecartridge deck interaction surface can each be on opposite sides of thescaffold and each can have fibers of a first polymer and fibers of asecond polymer, where the first polymer fibers can be multifilamentfibers. The first polymer fibers can form a structural component of thetissue interaction surface and the cartridge deck interaction surfacewith a variable stiffness profile over time following implantation. Thesecond polymer fibers can degrade at a rate greater than that of thefirst polymer fibers without substantially affecting the stiffnessprofile of the structural component. The intermediate layer can beformed of monofilament fibers that are oriented in a direction that issubstantially non-parallel to the cartridge deck. In one aspect, themultifilament fibers can have an average diameter that is greater than adiameter of the monofilament fibers. In another aspect, the scaffold canbe configured to apply a stress of at least about 3 g/mm² to thecaptured tissue for at least 3 days when the scaffold is in a tissuedeployed state.

In some aspects, the multifilament fibers can each include the secondpolymer fibers at a range of about 15% to 85%. In other aspects, themultifilament fibers can each include the second polymer fibers at arange of about 25% to 45%.

In some aspects, the second polymer fibers can have a fiber diameterfrom about 0.005 mm to 0.02 mm. In one aspect, the second polymer fiberscan be formed of a copolymer of glycolide and L-lactide.

In some aspects, the multifilament fibers can include about 6 to 40filaments. In one aspect, the filaments are formed of the first polymerfibers. In another aspect, at least one filament is formed of the firstpolymer fiber and at least one filament is formed of the second polymerfiber.

In some aspects, the first polymer fibers can be formed of at least oneof poly-L-lactic acid, a copolymer of glycolide and L-lactide, acopolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide.

In some aspects, the monofilament fibers can be formed of at least oneof polydioxanone, a copolymer of polydioxanone and polyglycolide, acopolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

In one exemplary embodiment, a scaffold is provided and can include atissue interaction surface and a cartridge deck interaction surface, andan intermediate layer disposed between the tissue interaction surfaceand the cartridge deck interaction surface. The tissue interactionsurface and a cartridge deck interaction surface can each be on oppositesides of the scaffold and each can have fibers of a first polymer andfibers of a second polymer, where the first polymer fibers can bemultifilament fibers. The first polymer fibers can form a structuralcomponent of the tissue interaction surface and the cartridge deckinteraction surface with a variable stiffness profile over timefollowing implantation. The second polymer fibers can degrade at a rategreater than that of the first polymer fibers without substantiallyaffecting the stiffness profile of the structural component. Theintermediate layer being can formed of monofilament fibers that areoriented in a direction that is substantially non-parallel to thecartridge deck. In another aspect, the scaffold can be configured toapply a stress of at least about 3 g/mm² to the captured tissue for atleast 3 days when the scaffold is in a tissue deployed state.

In some aspects, the multifilament fibers can have an average diameterthat is greater than a diameter of the monofilament fibers. In otheraspects, the multifilament fibers can each include the second polymerfibers at a range of about 15% to 85%.

In some aspects, the second polymer fibers can have a fiber diameterfrom about 0.005 mm to 0.02 mm. In one aspect, the second polymer fiberscan be formed of a copolymer of glycolide and L-lactide.

In some aspects, the multifilament fibers can include about 6 to 40filaments. In one aspect, at least one filament is formed of the firstpolymer fiber and at least one filament is formed of the second polymerfiber.

In some aspects, the first polymer fibers can be formed of at least oneof poly-L-lactic acid, a copolymer of glycolide and L-lactide, acopolymer of glycolic acid and lactic acid, poly(lactic-co-glycolicacid), poly(lactic acid), polyglycolide, and a copolymer of glycolide,caprolactone, trimethylene carbonate, and lactide.

In some aspects, the monofilament fibers can be formed of at least oneof polydioxanone, a copolymer of polydioxanone and polyglycolide, acopolymer of lactide and polycaprolactone), a copolymer of glycolide,dioxanone, and trimethylene carbonate, poly(trimethylene carbonate),polyhydroxyalkanoate, and polyglyconate.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

This invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of one exemplary embodiment of aconventional surgical stapling and severing instrument;

FIG. 2 is a perspective view of a wedge sled of a staple cartridge ofthe surgical stapling and severing instrument of FIG. 1;

FIG. 3 is a perspective view of a knife and firing bar (“E-beam”) of thesurgical stapling and severing instrument of FIG. 1;

FIG. 4 is a longitudinal cross-sectional view of a surgical cartridgethat can be disposed within the stapling and severing instrument of FIG.1;

FIG. 5 is a top view of a staple in an unfired (pre-deployed)configuration that can be disposed within the staple cartridge of thesurgical cartridge assembly of FIG. 4;

FIG. 6 is a longitudinal cross-sectional view of an exemplary embodimentof a surgical cartridge assembly having a scaffold attached to acartridge deck;

FIG. 7 is a schematic illustrating the scaffold of FIG. 6 when stapledto tissue;

FIG. 8A is a magnified top view of an exemplary embodiment of a scaffoldthat can be attached to the cartridge deck of the surgical cartridgeassembly of FIG. 6;

FIG. 8B is a magnified cross-sectional view of the scaffold of FIG. 8Ataken at B-B;

FIG. 8C is another magnified cross-sectional view of the scaffold ofFIG. 8A taken at C-C;

FIG. 9 is a scanning electron micrograph (SEM) image of the scaffold inFIGS. 8A-8C at 500 μm scale;

FIG. 10A is a histopathology image of an implanted scaffold removed at60 days as discussed in Example 2.

FIG. 10B is a magnified view of section 10B in FIG. 10A;

FIG. 11A is a histopathology image of an implanted scaffold removed at90 days as discussed in Example 2;

FIG. 11B is a magnified view of section 11B in FIG. 11A;

FIG. 12A is a perspective view of another exemplary embodiment of ascaffold;

FIG. 12B is another exemplary embodiment of a staple cartridge assemblyhaving the scaffold shown in FIG. 12A attached to a cartridge deck; and

FIG. 13 is a bottom view of another exemplary embodiment of a scaffold.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the instruments and methods disclosed herein.One or more examples of these embodiments are illustrated in theaccompanying drawings. Those skilled in the art will understand that theinstruments, systems, and methods specifically described herein andillustrated in the accompanying drawings are non-limiting exemplaryembodiments and that the scope of the present invention is definedsolely by the claims. The features illustrated or described inconnection with one exemplary embodiment may be combined with thefeatures of other embodiments. Such modifications and variations areintended to be included within the scope of the present invention.

Further, in the present disclosure, like-named components of theembodiments generally have similar features, and thus within aparticular embodiment each feature of each like-named component is notnecessarily fully elaborated upon. Additionally, to the extent thatlinear or circular dimensions are used in the description of thedisclosed systems, instruments, and methods, such dimensions are notintended to limit the types of shapes that can be used in conjunctionwith such systems, instruments, and methods. A person skilled in the artwill recognize that an equivalent to such linear and circular dimensionscan easily be determined for any geometric shape. Sizes and shapes ofthe systems and instruments, and the components thereof, can depend atleast on the anatomy of the subject in which the systems and instrumentswill be used, the size and shape of components with which the systemsand instruments will be used, and the methods and procedures in whichthe systems and instruments will be used.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a user, such as a clinician, gripping a handleof an instrument. Other spatial terms such as “front” and “rear”similarly correspond respectively to distal and proximal. It will befurther appreciated that for convenience and clarity, spatial terms suchas “vertical” and “horizontal” are used herein with respect to thedrawings. However, surgical instruments are used in many orientationsand positions, and these spatial terms are not intended to be limitingand absolute.

Values or ranges may be expressed herein as “about” and/or from/of“about” one particular value to another particular value. When suchvalues or ranges are expressed, other embodiments disclosed include thespecific value recited and/or from/of the one particular value toanother particular value. Similarly, when values are expressed asapproximations, by the use of antecedent “about,” it will be understoodthat here are a number of values disclosed therein, and that theparticular value forms another embodiment. It will be further understoodthat there are a number of values disclosed therein, and that each valueis also herein disclosed as “about” that particular value in addition tothe value itself. In embodiments, “about” can be used to mean, forexample, within 10% of the recited value, within 5% of the recited valueor within 2% of the recited value.

For purposes of describing and defining the present teachings, it isnoted that unless indicated otherwise, the term “substantially” isutilized herein to represent the inherent degree of uncertainty that maybe attributed to any quantitative comparison, value, measurement, orother representation. The term “substantially” is also utilized hereinto represent the degree by which a quantitative representation may varyfrom a stated reference without resulting in a change in the basicfunction of the subject matter at issue.

Surgical staple cartridge assemblies and methods for manufacturing thesame are provided. In general, a staple cartridge assembly is providedhaving a staple cartridge that includes a cartridge deck with aplurality of staples disposed therein. The staple cartridge assemblyalso includes a knitted elastically deformable, bioabsorbable scaffoldthat is configured to releasably mate with the cartridge deck and allowthe staples to be deployed therethrough into tissue. The scaffold can bereleasably mated to the cartridge deck such that when a staple isdeployed from the cartridge deck and into tissue, at least a portion ofthe scaffold can attach to the tissue captured by the staple. Asdiscussed herein, the scaffold can be configured to compensate forvariations in tissue properties, such as variations in the tissuethickness, and/or promote tissue ingrowth when the scaffold is stapledto tissue. For example, the scaffold can be configured to apply a stressof at least about 3 g/mm² to tissue for at least 3 days when in a tissuedeployed state (e.g., when the scaffold is stapled to tissue in vivo).An exemplary staple cartridge assembly can include a variety of featuresto facilitate application of a surgical staple, as described herein andillustrated in the drawings. However, a person skilled in the art willappreciate that the staple cartridge assembly can include only some ofthese features and/or it can include a variety of other features knownin the art. The staple cartridge assemblies described herein are merelyintended to represent certain exemplary embodiments. Moreover, while thescaffolds are described in connection with surgical staple cartridgeassemblies, the scaffolds can be used in connection with any type ofsurgical instrument.

FIG. 1 illustrates an exemplary surgical stapling and severinginstrument 100 suitable for use with an implantable adjunct such as, forexample, a scaffold. The surgical stapling and severing instrument 100can include an anvil 102 which may be repeatedly opened and closed aboutits pivotal attachment to an elongate staple channel 104. A stapleapplying assembly 106 may comprise the anvil 102 and the channel 104,wherein the assembly 106 can be proximally attached to an elongate shaft108 forming an implement portion 110. When the staple applying assembly106 is closed, or at least substantially closed, the implement portion110 can present a sufficiently small cross-section suitable forinserting the staple applying assembly 106 through a trocar. While theinstrument 100 is configured to staple and sever tissue, surgicalinstruments configured to staple but not sever tissue is alsocontemplated herein.

In various instances, the staple applying assembly 106 is manipulated bya handle 112 connected to the elongate shaft 108. The handle 112 caninclude user controls such as a rotation knob 114 that rotates theelongate shaft 108 and the staple applying assembly 106 about alongitudinal axis of the elongate shaft 108 and a closure trigger 116,which can pivot in front of a pistol grip 118 to close the stapleapplying assembly 106. A closure release button 120 is outwardlypresented on the handle 112 when the closure trigger 116 is clamped suchthat the closure release button 120 can be depressed to unclamp theclosure trigger 116 and open the staple applying assembly 106, forexample.

A firing trigger 122, which can pivot in front of the closure trigger116, causes the staple applying assembly 106 to simultaneously sever andstaple tissue clamped therein. In various instances, multiple firingstrokes can be employed using the firing trigger 122 to reduce theamount of force required to be applied by the surgeon's hand per stroke.In certain embodiments, the handle 112 can comprise one or morerotatable indicator wheels such as, for example, rotatable indicatorwheel 124 which can indicate the firing progress. A manual firingrelease lever 126 can allow the firing system to be retracted beforefull firing travel has been completed, if desired, and, in addition, thefiring release lever 126 can allow a surgeon, or other clinician, toretract the firing system in the event that the firing system bindsand/or fails.

Additional details on the surgical stapling and severing instrument 100and other surgical stapling and severing instruments suitable for usewith the present disclosure are described, for example, in U.S. Pat. No.9,332,984 and in U.S. Patent Application Publication No. 2009/0090763,the disclosures of which are incorporated herein by reference in theirentirety. Further, the surgical stapling and severing instrument neednot include a handle, but instead a housing that is configured to coupleto a surgical robot, for example, as described in U.S. patentapplication Ser. No. 15/689,198, filed on Aug. 29, 2017 to Frederick E.Shelton et al., the disclosure of which is incorporated herein byreference in its entirety.

With reference to FIGS. 2 and 3, a firing assembly such as, for example,firing assembly 228 can be utilized with a surgical stapling andsevering instrument, such as instrument 100 in FIG. 1, to advance awedge sled 230 which comprises a plurality of wedges 232 configured todeploy staples from a staple applying assembly, like staple applyingassembly 106 in FIG. 1 into tissue captured between an anvil, like anvil102 in FIG. 1 and an elongate staple channel, like channel 104 inFIG. 1. Furthermore, an E-beam 233 at a distal portion of the firingassembly 228 may fire the staples from the staple applying assembly aswell as position the anvil relative to the elongate staple channelduring firing. The E-beam 233 includes a pair of top pins 234, a pair ofmiddle pins 236 which may follow portion 238 of the wedge sled 230, anda bottom pin or foot 240, as well as a sharp cutting edge 242, which canbe configured to sever the captured tissue as the firing assembly 228 isadvanced distally. In addition, integrally formed and proximallyprojecting top guide 244 and middle guide 246 bracketing each verticalend of the cutting edge 242 may further define a tissue staging area 248assisting in guiding tissue to the sharp cutting edge 242 prior to beingsevered. The middle guide 246 may also serve to engage and fire thestaple applying assembly by abutting a stepped central member 250 of thewedge sled 230 that effects staple formation by the staple applyingassembly.

Referring to FIG. 4, a staple cartridge 400 can be utilized with asurgical stapling and severing instrument, like surgical stapling andsevering instrument 100 in FIG. 1, and can include a cartridge deck 402and a plurality of staple cavities 404. A staple 406, for example, canbe removably positioned in each staple cavity 404. The staple 406 in aunfired (pre-deployed) configuration is shown in more detail in FIG. 5.The staple cartridge 400 can also include a longitudinal channel thatcan be configured to receive a firing and/or cutting member, e.g., anE-beam, like E-beam 233 in FIG. 3.

Each staple 406 can comprise a crown (base) 406 _(C) and one or morelegs 406 _(L) extending from the crown 406 _(C). Prior to the staples406 being deployed, the crowns 406 _(C) of the staples 406 can besupported by staple drivers 408 positioned within the staple cartridge400 and, concurrently, the legs 406 _(L) of the staples 406 can be atleast partially contained within the staple cavities 404. Further, thestaple legs 406 _(L) of the staples 406 can extend beyond thetissue-contacting surface 410 of the staple cartridge 400 when thestaples 406 are in their unfired positions. In certain instances, asshown in FIG. 5, the tips of the staple legs 406 _(L) can comprise sharptips which can incise and penetrate tissue.

The staples 406 can be deployed between an unfired position and a firedposition such that the legs 406 _(L) move through the staple cavities404, penetrate tissue positioned between an anvil, like anvil 102 inFIG. 1, and the staple cartridge 400, and contact the anvil. As the legs406 _(L) are deformed against the anvil, the legs 406 _(L) of eachstaple 406 can capture a portion of the tissue within each staple 406and apply a compressive force to the tissue. Further, the legs 406 _(L)of each staple 406 can be deformed downwardly toward the crown 406 _(C)of the staple 406 to form a staple entrapment area in which the tissuecan be captured therein. In various instances, the staple entrapmentarea can be defined between the inner surfaces of the deformed legs andthe inner surface of the crown of the staple. The size of the entrapmentarea for a staple can depend on several factors such as the length ofthe legs, the diameter of the legs, the width of the crown, and/or theextent in which the legs are deformed, for example.

In use, an anvil, like anvil 102 in FIG. 1, can be moved into a closedposition by depressing a closure trigger, like closure trigger 116 inFIG. 1, to advance an E-beam, like E-beam 233 in FIG. 3. The anvil canposition tissue against a tissue-contacting surface 410 of the staplecartridge 400. Once the anvil has been suitably positioned, the staples406 can be deployed.

To deploy staples 406, as discussed above, a staple-firing sled, likesled 230 in FIG. 2, can be moved from a proximal end 400 p toward adistal end 400 d of the staple cartridge 400. As a firing assembly, likefiring assembly 228 in FIG. 3, is advanced, the sled can contact thestaple drivers 408 and lift the staple drivers 408 upwardly within thestaple cavities 404. In at least one example, the sled and the stapledrivers 408 can each include one or more ramps, or inclined surfaces,which can co-operate to move the staple drivers 408 upwardly from theirunfired positions. As the staple drivers 408 are lifted upwardly withintheir respective staple cavities 404, the staple drivers 408 can liftthe staples 406 upwardly such that the staples 406 can emerge from theirstaple cavities 404 and penetrate into tissue. In various instances, thesled can move several staples upwardly at the same time as part of afiring sequence.

A person skilled in the art will appreciate that, while scaffolds areshown and described below, the scaffolds disclosed herein can be usedwith other surgical instruments, and need not be coupled to a staplecartridge as described.

As discussed above, with some surgical staplers, a surgeon is oftenrequired to select the appropriate staples having the appropriate stapleheight for the tissue that is to be stapled. For example, a surgeoncould select tall staples for use with thick tissue and short staplesfor use with thin tissue. In some instances, however, the tissue beingstapled does not have a consistent thickness and, thus, the staplescannot achieve the desired fired configuration for every section of thestapled tissue (e.g., thick and thin tissue sections). The inconsistentthickness of tissue can also lead to undesirable leakage and/or tearingof tissue at the staple site when staples with the same or substantiallyheight are used, particularly when the staple site is exposed tointra-tissue pressures at the staple site and/or along the staple line.

Accordingly, various embodiments of scaffolds are provided that can beconfigured to compensate for varying thickness of tissue that iscaptured within fired (deployed) staples to avoid the need to take intoaccount staple height when stapling tissue during surgery. That is, thescaffolds described herein can allow a set of staples with the same orsimilar heights to be used in stapling tissue of varying thickness(i.e., from thin to thick tissue) while also, in combination with thescaffold, provide adequate tissue compression within and between firedstaples. Thus, the scaffolds described herein can maintain suitablecompression against thin or thick tissue stapled thereto to therebyminimize leakage and/or tearing of tissue at the staple sites.

Alternatively or in addition, the scaffold can be configured to promotetissue ingrowth. In various instances, it is desirable to promote theingrowth of tissue into an implantable scaffold, to promote the healingof the treated tissue (e.g. stapled and/or incised tissue) and/or toaccelerate the patient's recovery. More specifically, the ingrowth oftissue into an implantable scaffold may reduce the incidence, extent,and/or duration of inflammation at the surgical site. Tissue ingrowthinto and/or around the implantable scaffold may manage the spread ofinfections at the surgical site, for example. The ingrowth of bloodvessels, especially white blood cells, for example, into and/or aroundthe implantable scaffold may fight infections in and/or around theimplantable scaffold and the adjacent tissue. Tissue ingrowth may alsoencourage the acceptance of foreign matter (e.g., the implantablescaffold and the staples) by the patient's body and may reduce thelikelihood of the patient's body rejecting the foreign matter. Rejectionof foreign matter may cause infection and/or inflammation at thesurgical site.

In general, the scaffolds provided herein are designed and positionedatop a staple cartridge, like staple cartridge 400 in FIG. 4, such thatwhen the staples are fired (deployed) from the cartridge deck of thestaple cartridge, the staples penetrate through the scaffold and intotissue. As the legs of the staple are deformed against the anvil that ispositioned opposite the staple cartridge assembly, the deformed legscapture a portion of the scaffold and a portion of the tissue withineach staple. That is, when the staple is fired into tissue, at least aportion of the scaffold becomes positioned between the tissue and thefired staple. While the scaffolds described herein are configured to beattached to a staple cartridge of a staple cartridge assembly, it isalso contemplated herein that the scaffolds can be configured to matewith other instrument components, such as a jaw of a surgical stapler.

FIG. 6 illustrates an exemplary embodiment of a staple cartridgeassembly 600 that includes a staple cartridge 602 and a scaffold 604.Aside from the differences described in detail below, the staplecartridge 602 can be similar to staple cartridge 400 (FIG. 4) and istherefore not described in detail herein. As shown, the scaffold 604 ispositioned against the staple cartridge 602. The staple cartridge caninclude a cartridge deck 606 and a plurality of staples 608, likestaples 406 shown in FIGS. 4 and 5. The staples 608 can be any suitableunformed (pre-deployed) height. For example, the staples 608 can have anunformed height between about 2 mm to 4.8 mm. Prior to deployment, thecrowns of the staples 608 can be supported by staple drivers 610.

In the illustrated embodiment, the scaffold 604 can be mated to an outersurface 612, for example a tissue-contacting surface, of the cartridgedeck 606. The outer surface 612 of the cartridge deck 606 can includeone or more attachment features. The one or more attachments featurescan be configured to engage the scaffold 604 to avoid undesirablemovements of the scaffold 604 relative to the cartridge deck 606 and/orpremature release of the scaffold 604 from the cartridge deck 606.Exemplary attachment features can be found in U.S. Patent PublicationNo. 2016/0106427, which is incorporated by reference herein in itsentirety.

The scaffold 604 is elastically deformable to permit the scaffold tocompress to varying heights to thereby compensate for different tissuethickness that are captured within a deployed staple. The scaffold 604has an uncompressed (undeformed), or pre-deployed, height and isconfigured to deform to one of a plurality of compressed (deformed), ordeployed, heights. For example, the scaffold 604 can have anuncompressed height which is greater than the fired height of thestaples 608 (e.g., the height (H) of the fired staple 608 a in FIG. 7).In one embodiment, the uncompressed height of the scaffold 604 can beabout 10% taller, about 20% taller, about 30% taller, about 40% taller,about 50% taller, about 60% taller, about 70% taller, about 80% taller,about 90% taller, or about 100% taller than the fired height of thestaples 608. In certain embodiments, the uncompressed height of thescaffold 604 can be over 100% taller than the fired height of thestaples 608, for example.

The scaffold 604 can be releasably mated to the outer surface 612 of thecartridge deck 606. As shown in FIG. 7, when a staple is fired, tissue(T) and a portion of the scaffold 604 is captured by the fired (formed)staple 608 a. The fired staple 608 a defines the entrapment areatherein, as discussed above, for accommodating the captured scaffold 604and tissue (T). The entrapment area defined by the fired staple 608 a islimited, at least in part, by a height (H) of the fired staple 608 a.For example, the height of a fired staple 608 a can be about 0.130inches or less. In some embodiments, the height of a fired staple 608 acan be from about 0.025 inches to 0.130 inches. In some embodiments, theheight of a fired staple 608 a can be from about 0.030 inches to 0.100inches.

As described above, the scaffold 604 can be compressed within aplurality of fired staples whether the thickness of the tissue capturedwithin the staples is the same or different within each staple. In atleast one exemplary embodiment, the staples within a staple line, orrow, can be deformed such that the fired height is about 2.75 mm, forexample, where the tissue (T) and the scaffold 604 can be compressedwithin this height. In certain instances, the tissue (T) can have acompressed height of about 1.0 mm and the scaffold 604 can have acompressed height of about 1.75 mm. In certain instances, the tissue (T)can have a compressed height of about 1.50 mm and the scaffold 604 canhave a compressed height of about 1.25 mm. In certain instances, thetissue (T) can have a compressed height of about 1.75 mm and thescaffold 604 can have a compressed height of about 1.00 mm. In certaininstances, the tissue (T) can have a compressed height of about 2.00 mmand the scaffold 604 can have a compressed height of about 0.75 mm. Incertain instances, the tissue (T) can have a compressed height of about2.25 mm and the scaffold 604 can have a compressed height of about 0.50mm. Accordingly, the sum of the compressed heights of the capturedtissue (T) and scaffold 604 can be equal, or at least substantiallyequal, to the height (H) of the fired staple 608 a.

As discussed in more detail below, the structure of the scaffold can beconfigured such that when the scaffold and tissue are captured withinthe fired staple, the scaffold can apply a stress that can withstand thepressure of circulating blood through tissue. High blood pressure istypically considered 210 mmHg, and therefore it would be desirable forthe scaffold to apply a stress to the tissue that is equal to or greaterthan 210 mmHg (e.g., 3 g/mm²) for a predetermined time period (e.g., 3days). As such, in certain embodiments, the scaffold can be configuredto apply a stress of at least about 3 g/mm² to the captured tissue forat least 3 days. The scaffold is in a tissue deployed state when thescaffold is stapled to tissue in vivo. In one embodiment, the appliedstress can be about 3 g/mm². In another embodiment, the applied stresscan be greater than 3 g/mm². In yet another embodiment, the stress canbe at least about 3 g/mm² and applied to the captured tissue for morethan 3 days. For example, in one embodiment, the stress can be at leastabout 3 g/mm² and applied to captured tissue for about 3 days to 5 days.

In order to design a scaffold that is configured to apply a stress of atleast about 3 g/mm² to the captured tissue for a predetermined time, onecan use the principles of Hooke's law (F=kD). For example, when theforce (stress) to be applied to the captured tissue is known, one candesign a scaffold to have a stiffness (k). The stiffness can be set bytuning the materials and/or the geometry of the scaffold (e.g., the typeand/or diameter of the fibers and/or the interconnectivity of thefibers). Further, one can design the scaffold to have a maximum amountof compression displacement for a minimum thickness of tissue, e.g., 1mm, and therefore the length of displacement D can be the combination ofa minimum thickness of tissue, e.g., 1 mm, plus a thickness of thetissue when stapled to tissue for a given max staple height, e.g., 2.75mm. By way of example, in one embodiment, a scaffold can be structuredto have a height that is greater than a maximum formed stapled height of2.75 mm and to compress to a height of 1.75 mm when stapled to tissuehaving a minimum thickness of 1 mm. Therefore, the scaffold can vary incompressibility to maintain a constant length of displacement D suchthat the stiffness (k) and total thickness (D) of captured tissue andscaffold can apply a stress of 3 g/mm² to the captured tissue. It shouldbe noted a person of ordinary skill in the art will appreciate that theforegoing formula can be modified to take into account variations intemperatures, e.g., when the adjunct is brought from room temperature tobody temperature after implantation.

Additionally, the scaffold can be further developed to provide asubstantially continuous stress to the captured tissue (e.g., 3 g/mm²)for a predetermined time (e.g., 3 days). To achieve this, one would needto take into account the degradation rate of the materials of thescaffold and the rate of tissue ingrowth within the scaffold whendesigning the scaffold. In doing so, one can design a scaffold such thatthe stiffness of the scaffold and/or the total thickness of the capturedtissue and scaffold do not vary in a way that could effect an appliedstress that is less than 3 g/mm².

A scaffold is stapled to tissue under various stapling conditions (e.g.,tissue thickness, height of formed staple, intra-tissue pressure).Depending on the stapling condition, one can determine an effectiveamount of stress that the scaffold needs to be able to apply to thetissue to prevent tissue tearing and leakage. For example, in oneembodiment, an effective amount of stress is at least about 3 g/mm². Inorder for the scaffold to provide an effective amount of stress to thetissue, the scaffold can be designed to effectively compensate for thevarious stapling conditions. As such, the scaffold can be tailored toassume different compressed heights when stapled to tissue. As there isa finite range of intra-tissue pressures, tissue thicknesses, and formedstaple heights, one can determine appropriate material and/or geometricstructures for the scaffold that can be effective in applying asubstantially continuous desired stress to the tissue (e.g., 3 g/mm²)when stapled thereto for a given amount of time (e.g., at least 3 days)over a range of stapling conditions. That is, as described in moredetail below, the present scaffolds are formed of compressible materialsand geometrically configured so as to allow the scaffold to compress tovarious heights in predetermined planes when stapled to tissue. Further,this varied response by the scaffold can also allow the scaffold tomaintain its application of a continuous desired stress to the tissuewhen exposed to fluctuations in intra-tissue pressure that can occurwhen the scaffold is stapled to tissue (e.g., a spike in bloodpressure).

The scaffold can have a variety of configurations. For example, incertain embodiments, the scaffold can include at least one knitted layerand at least one support layer. As used herein, “knitted layer” is usedsynonymously with “knitted zone,” and “support layer” is usedsynonymously with “spacer zone.”

FIGS. 8A-8C and 9 illustrate an exemplary embodiment of a scaffold 800having first and second knitted layers 802, 804 with a support layer 806disposed therebetween. In this illustrated embodiment, the first knittedlayer 802 can be configured to be positioned against tissue and thesecond knitted layer 804 can be configured to be positioned against acartridge deck, like cartridge deck 606 in FIG. 6.

As shown, the knitted layers 802, 804 includes fibers 808 of a firsttype and fibers 810 of a second type, and the support layer 806 includesthe second type of fibers 810. In this way, by having the scaffold 800formed of two different fibers 808, 810 the scaffold can have a variablestiffness profile over time following implantation. For example, thefirst type of fibers 808 can function as a structural component of theknitted layers 802, 804, and the stiffness profile can be a function ofthe degradation profile of the first type of fibers 808 and theinteraction between the first type of fibers 808 with the second type offibers 810 in the knitted layers 802, 804.

Further, the knitted layers 802, 804 can be configured such that whenthe scaffold 800 is attached to a cartridge deck, at least a portion ofthe first type of fibers 808 are oriented in a direction that issubstantially parallel to the cartridge deck. While the first and secondtype of fibers 808, 810 can have a variety of sizes, in someimplementations, the first type of fibers 808 has a fiber diameter thatis less than a fiber diameter of the second type of fibers 810.

While the fibers 808, 810 of the knitted layers 802, 804 and of thesupport layer 806 can either be monofilament or multifilament, in someimplementations, the first type of fibers 808 are multifilament fibersand the second type of fibers 810 are monofilament fibers, as shown inFIGS. 8A-8C and 9. As used herein, the term “monofilament fibers” hasits own ordinary and customary meaning and can include fibers formed ofa single filament. As used herein, the term “multifilament fibers” hasits own ordinary and customary meaning and can include fibers formed oftwo or more filaments that are associated with one another to form aunitary structure. In one embodiment, the multifilament fibers arenon-bonded multifilament fibers. As used herein, a “non-bondedmultifilament fiber” has its own ordinary and customary meaning and caninclude an assembly of two or more filaments that are in contact withone another at least one point along their lengths but are notphysically attached to one another. Non-limiting examples of non-bondedmultifilament fibers include yarn (filaments twisted about one anotheralong their lengths) and tow (filaments not twisted about one anotheralong their lengths).

The multifilament fibers can have a variety of configurations. Forexample, in some implementations, each multifilament fiber includes fromabout 6 to 40 filaments. In one aspect, each multifilament fiberincludes from about 14 to 28 filaments. The increased surface area andvoids that exist between the filaments of the multifilament fibers canfacilitate improved tissue ingrowth within the scaffold (see e.g.,Example 2).

The multifilament fibers can have a variety of sizes. For example, eachmultifilament fiber can have an average diameter of about 0.02 mm to 0.2mm, of about 0.05 mm to 0.2 mm, or of about 0.15 mm to 0.2 mm. In someimplementations, each filament of the multifilament fibers has adiameter that is less than a fiber diameter of the monofilament fibers.For example, where the knitted layers 802, 804 include first type offibers that are multifilament fibers and second type of fibers that aremonofilament fibers, each filament of the multifilament fibers can havea diameter that is about ⅕ to 1/20 the diameter of the monofilamentfibers. In certain embodiments, each filament of the multifilamentfibers can have a diameter that is about 1/10 the diameter of themonofilament fibers.

The multifilament fibers can be formed of filaments formed of the samematerial or filaments of different materials. For example, in someimplementations, the multifilament fibers can include first filaments ofa first material and second filaments of a second material. In oneembodiment, the second material degrades at a faster rate than adegradation rate of the first material. In this way, the degradation ofthe second material can activate, and thus encourage acceleratedattraction of, macrophages and accelerate the inflammation phase ofhealing while not substantially affecting the variable stiffness profileof the scaffold over time following implantation. The activation ofmacrophages can in turn cause increases in myofibroblast population andneovascularization. Further, the degradation of the second material canencourage tissue ingrowth within the scaffold. The first material, forexample, can be at least one of poly-L-lactic acid, a copolymer ofglycolide and L-lactide, a copolymer of glycolic acid and lactic acid,poly(lactic-co-glycolic acid), poly(lactic acid), polyglycolide, and acopolymer of glycolide, caprolactone, trimethylene carbonate, andlactide. Non-limiting examples of suitable first materials can be formedof polyglactin 910, Lactomer™ 9-1, 75:25 or 50:50 lactic acid/glycolicacid, Polygytone™ 6211, or Caprosyn™. The second material, for example,can be a copolymer of glycolide and L-lactide, such as Vicryl Rapide™.

While the multifilament fibers can include the second filaments atvarious percentage ranges, in some implementations, the multifilamentfibers can each include second filaments at a range of about 15% to 85%or at a range of about 25% to 45%. The second filaments can have variousfiber diameters. For example, in some implementations, the secondfilaments can have a fiber diameter from about 0.0005 mm to 0.02 mm. Inone embodiment, the second filaments have a fiber diameter of about0.015 mm.

The monofilament fibers can have a variety of sizes. For example, themonofilaments can have a diameter of about 0.2 mm to 0.35 mm. In someimplementations, the monofilament fibers can each have a diameter thatis less than an average diameter of the multifilament fibers. Theaverage diameter (D) of a multifilament fiber can be calculated usingthe following formula:

$D = \sqrt{\frac{4W}{N\;{\rho\pi}}}$where,

-   -   W=weight of multifilament fiber (fiber bundle) per unit length    -   N=number of filaments    -   ρ=density of fiber.

While the first and second type of fibers 808, 810 can have variousglass transition temperatures, in some implementations, the first typeof fibers 808 have a first glass transition temperature and the secondtype of fibers 810 have a second glass transition temperature that isless than the first glass transition temperature. For example, the firstglass transition temperature can be greater than the second glasstransition temperature by at least about 30 degrees C. In otherexemplary embodiments, the first glass transition temperature can begreater than the second glass transition temperature by at least about45 degrees C. A difference in glass transition of the first and secondtypes of fibers 808, 810 can further facilitate a secure attachment ofthe scaffold to the cartridge deck without adversely affecting thestructural integrity of the scaffold.

As discussed above, a portion of the scaffold is captured with tissuewithin the fired staple and therefore it is desirable that the scaffoldbe formed of suitable bioabsorbable materials. As such, the first andsecond type of fibers 808, 810 can each be formed of a variety ofabsorbable materials. Non-limiting examples of suitable materials forthe first type of fibers include at least one of poly-L-lactic acid, acopolymer of glycolide and L-lactide, a copolymer of glycolic acid andlactic acid, poly(lactic-co-glycolic acid), poly(lactic acid),polyglycolide, and a copolymer of glycolide, caprolactone, trimethylenecarbonate, and lactide. For example, the first type of fibers can beformed of polyglactin 910, Lactomer™ 9-1, 75:25 or 50:50 lacticacid/glycolic acid, Polygytone™ 6211, or Caprosyn™. Non-limitingexamples of suitable materials for the second type of fibers include atleast one of polydioxanone, a copolymer of polydioxanone andpolyglycolide, a copolymer of lactide and polycaprolactone), a copolymerof glycolide, dioxanone, and trimethylene carbonate, poly(trimethylenecarbonate), polyhydroxyalkanoate, and polyglyconate. For example, thesecond type of fibers can be formed of 92:8 polydioxanone/Polyglycolide,25:75 lactide/polycaprolactone, Glycomer™ 631, or Maxon™. In oneembodiment, the first type of fibers is formed of polyglactin 910 andthe second type of fibers is formed of polydioxanone.

In some embodiments, the first type of fibers 808 can be coated with abioabsorbable polymeric material. In this way, the glass transitiontemperature of the first type of fibers 808 can be modified, e.g., byeither increasing or decreasing the glass transition compared to theglass transition temperature of the base material of the first type offibers, which in certain instances may be desirable for attaching thescaffold to the cartridge deck. For example, decreasing the glasstransition temperature of the first type of fibers 808 can provide amore secure attachment of the scaffold 800 to a cartridge deck, likecartridge deck 606 in FIG. 6, and/or enhance the conformability of thescaffold 800 to the cartridge deck and, when cooled, maintain a suitableshape. Non-limiting examples of suitable coating materials includepolydioxanone or 25:75 lactide/polycaprolactone.

While the knitted layers 802, 804 can each have various knittedpatterns, in some implementations, like in FIGS. 8A-8C and 9, theknitted layers 802, 804 can each have a Rachel knit pattern (e.g., asdescribed in Example 1 below). A person skilled in the art willappreciate that the knitted layers of the scaffold can take the form ofother warp knitted patterns.

As shown in FIGS. 8A-8C and 9, the second type of fibers 810interconnect with the first type of fibers 808 of the first and secondknitted layers 802, 804 in a manner in which the first and second fibersare non-fixedly attached and slidably interconnected. As such, in thisillustrated embodiment, the first and second type of fibers 808, 810 canmove relative to each other, thereby allowing for movement and forexpansion in the x-direction (e.g., stretch) and the y-direction (e.g.,compression). Additionally, the interconnection between the first andsecond type of fibers 808, 810 can affect, at least in part, thestiffness of the scaffold 800. For example, the tighter theinterconnection, the stiffer the scaffold 800.

Further, as shown in the FIGS. 8A-8C and 9, the first and second knittedlayers 802, 804 each include a plurality of openings 812 formed therein.The openings 812 of the first and second knitted layers 802, 804 eachhave a perimeter formed of the first and second types of fibers 808,810. The openings 812 of the second knitted layer 804 can have a sizethat is less than about ¼ of a width of a crown of a staple, like staple406 in FIG. 5. As such, in some implementations, the crown of the firedstaple can span over at least four openings 812 in the second knittedlayer 804. In one embodiment, the openings 812 can have a size that isabout ⅛ of the width of the crown. While the crown of a staple can havea variety of widths, in some implementations, the width of the crown canbe about 0.080 inches to 0.140 inches. In one embodiment, the width ofthe crown is about 0.12 inches.

The plurality of openings 812 in the first and second knitted layers802, 804 can have a variety of sizes. For example, the plurality ofopenings 812 in the second knitted layer 804 can have a diameter fromabout 0.002 inches to 0.1 inches. As used herein, “diameter” of anopening is the largest distance between any pair of vertices of theopening.

As discussed above and shown in FIGS. 8A-8C and 9, the scaffold 800includes a support layer 806 that is positioned between the first andsecond knitted layers 802, 804. The support layer 806 is non-fixedlyattached to first and second knitted layers 802, 804. The support layer806 can be configured such that when the scaffold 800 is attached to acartridge deck, like cartridge deck 606 in FIG. 6, at least a portion ofthe second type of fibers 810 of the support layer 806 are oriented in adirection that is substantially non-parallel to the cartridge deck.While the support layer 806 is shown in FIGS. 8A-8C and 9, to includeonly the second type of fibers 810, which in this exemplary embodiment,are monofilaments, it is also contemplated herein that the support layer806 can include additional types of fibers, including, for example, thefirst type of fibers 808.

As shown, the fibers 810 of the support layer 806 are arranged withinthe support layer 806 to form standing (spacer) fibers 814 and aplurality of voids 816 therebetween. The standing fibers 814 arenon-fixedly attached to each other. Further, the standing fibers 814 arenon-fixedly and slidably interconnected to the first type of fibers 808of the first and second knitted layers 802, 804. In someimplementations, the plurality of voids 816 can be larger than theplurality of openings 812 in the first and second knitted layers 802,804.

The standing fibers 814 are configured to bend under force applied tothe scaffold 800 (e.g., when stapled to tissue). The resilience of thestanding fibers 814 permits, at least in part, the scaffold to compressat various heights to thereby accommodate tissue (T) with tissueportions of different thicknesses. That is, independent of theparticular tissue thickness, the sum of the compressed heights of thecaptured tissue and scaffold within the fired staple can be maintained,and thus can remain equal, or at least substantially equal, to theheight of the fired staple. In this way, at least in part, the scaffold800 can be configured to apply a stress of at least about 3 g/mm² to thecaptured tissue for at least a predetermined period (e.g., at leastabout 3 days).

Generally, the material composition, the height, and/or the transversecross-sectional area of each standing fiber 814 controls, at least inpart, its stiffness or ability to bend under compression which, in turn,controls, at least in part, the compressibility of the scaffold 800.Accordingly, the standing fibers 814 can be configured to tune thecompressibility of the scaffold 800 to one or more desired values. Forexample, while the standing fibers 814 in FIGS. 8B-8C and 9 are of thesame material, in some implementations, the support layer 806 caninclude standing fibers of different materials with differentstiffnesses. Alternatively or in addition, in some implementations, thesupport layer 806 can include standing fibers of different heightsand/or transverse cross-sectional areas. In one embodiment, the standingfibers 814 can have a high length-to-diameter ratio, for example, aratio of about 25:1 to 6:1. In this way, the standing fibers 814 canfurther encourage tissue ingrowth and cell integration within theimplanted scaffold.

The amount of the standing fibers 814 within a certain section of thesupport layer 806 can also affect, among other things, thecompressibility of such section, and thus the compressibility of thescaffold 800. In certain instances, the standing fibers 814 can bestrategically concentrated in certain sections of the support layer 806to provide greater column strength in such sections, for example. In atleast one instance, the standing fibers 814 can be concentrated insections of the support layer 806 that are configured to receive stapleswhen the staples are fired. Alternatively, the standing fibers 814 canbe concentrated in sections of the support layer 806 that do not receivestaples when the staples are fired.

The ratio of the voids 816 to the standing fibers 814 can vary. In oneimplementation this ratio can be in the range of at least about 3:1. Inother implementations, the ratio of voids 816 to the standing fibers 814can in the range of at least about 5:1 or of at least about 12:1.Further, at least a portion of the voids 816 in the support layer 806can each have a different size. In this way, the variable void sizesthroughout the cross-section of the scaffold 800 can promoteextracellular remodeling. That is, the variable void sizes canfacilitate revascularization as well as mobility of cells within thescaffold 800 when the scaffold is implanted, thereby encouraging bothtissue and cellular ingrowth. Further the variable void sizes can alsofacilitate extraction of byproducts and cellular waste from theimplanted scaffold, and thus the implantation site.

In some embodiments, the scaffold 800 can also include a porous layerinterconnected to the second knitted layer 804. In this way, when thescaffold 800 is attached to a cartridge deck, like cartridge deck 606 inFIG. 6, the porous layer would be positioned between the cartridge deckand the second knitted layer 804. In one embodiment, the porous layer isfused or bonded to the second knitted layer 804. The porous layer can beformed of a material having a lower glass transition temperature thanthe fibers 808, 810 of the scaffold 800. It is also contemplated hereinthat the porous layer can be formed of a material having the same or ahigher glass transition temperature than at least one of the fibers 808,810 of the scaffold 800. The porous layer can have a thickness that isless than about 0.003 inches. In one embodiment, the porous layer has athickness that is less than about 0.001 inches. The porous layer canalso include pores that are greater than about 0.0005 inches indiameter. For example, in some implementations, the pores can vary insize from about 0.0005 inches to about 0.001 inches. Further, in someimplementations, the pores can make up at 50% of the surface area of thelayer.

The scaffolds described herein, like scaffold 800 in FIGS. 8A-8C and 9,can be manufactured using any suitable methods. For example, in oneembodiment, the method can include forming a first knitted layer,forming a second knitted layer, and interknitting spacers with the firstand second knitted layers. The first and second knitted fibers cancomprise fibers of a first polymer. The first knitted layer can beconfigured to mate with a cartridge deck. Interknitting the spacerfibers with the first and second knitted layers can connect the firstand second knitted layers together in a spaced parallel relation. Asused herein, a “spaced parallel relation” means that the first andsecond layers extend within planes that are distanced from andsubstantially parallel with one another. The spacer fibers can be formedof only a second polymer that is different than the first polymer. Thefirst polymer fibers can have a diameter that is different than adiameter of the second polymer fibers. The spacer fibers can beintegrated with and extending between the first and second knittedlayers. The method can also include annealing the first and secondknitted layers interknitted with the spacer fibers.

The interknitting of the spacer fibers with the first and second knittedlayers can form a support layer therebetween. The formation of the firstknitted layer can include knitting the first polymer fibers according toa predetermined pattern. The formation of the second knitted layer caninclude knitting the first polymer fibers according to a predeterminedpattern. While the knitted layers can each have various knittedpatterns, in some implementations, the knitted layers can each have aRachel knit pattern (e.g., as described in Example 1 below). A personskilled in the art will appreciate that the knitted layers of thescaffold can take the form of other warp knitted patterns.

FIG. 12A illustrates another exemplary embodiment of a scaffold 1000.Aside from the differences described in detail below, the scaffold 1000can be similar in construction to the scaffold 800 (FIGS. 8A-8C and 9)and is therefore not described in detail herein. In this embodiment, thescaffold 1000 includes a first knitted layer 1002 having a first portion1004 and a second portion 1006, each having outer and inner edges. Theinner edges 1004 a, 1006 a define a channel 1008 that extends along thelongitudinal axis (L) of the scaffold 1000. The channel 1008 isconfigured to receive a cutting member, such as a knife. As shown inFIG. 12B, the channel 1008 does not extend completely through thescaffold 1000. In particular, the channel 1008 does not extend throughthe second knitted layer 1010. In this way, the scaffold 1000 isconfigured to have sufficient structural integrity to thereby beeffectively manipulated and attached to a cartridge deck, like cartridgedeck 2014 in FIG. 12B. In another embodiment, as shown in FIG. 13, thescaffold 3000 can have a channel 3008 that is perforated. In use, whenthe cutting member is initially fired and travels along the scaffold1000, the cutting member cuts through the second knitted layer 1010,thereby separating the scaffold 1000 into two pieces.

Further, as shown in FIG. 12A, the scaffold 1000 includes flanges 1012that are configured to mate with recessed channels, like recessedchannels 2016 of cartridge deck 2014 in FIG. 12B, as further describedbelow. While FIG. 12A illustrates the scaffold 1000 having flanges 1012at one side of the scaffold 1000, there are additional flanges 1012positioned at the opposite side of the scaffold 1000. A person skilledin the art will appreciate that the number and placement of flanges 1012are not limited to what is shown in FIG. 12A. While the flanges 1012 canbe made of a variety of materials, in some implementations, as shown inFIG. 12A, the flanges 1012 are an extension of the second knitted layer1010. In other embodiment, the flanges 1012 can be formed of differentmaterial and formed in-line or offline with the other components of thescaffold 1000. A person skilled in the art will appreciate that theflanges can be formed of the same or different materials than that ofthe first and/or second knitted layers of the scaffold and can beattached thereto by any suitable method.

FIG. 12B illustrates another exemplary embodiment of a staple cartridgeassembly 2000. Aside from the differences described in detail below, thestaple cartridge assembly 2000 can be similar to staple cartridgeassembly 600 (FIG. 6) and is therefore not described in detail herein.Further, for purposes of simplicity, certain components of the staplecartridge assembly 2000 are not illustrated in FIG. 12B.

The staple cartridge assembly 2000 includes the scaffold 1000 in FIG.12A attached to a cartridge deck 2014 having recessed channels 2016. Thescaffold 1000 can be attached to the cartridge deck using any suitablemethods, as described in more detail below. As shown, the recessedchannels 2016 are configured to receive the flanges 1012 such that theflanges 1012 can attach to the side(s) of the cartridge deck. In thisway, the scaffold 1000 can be more securely attached to the cartridgedeck 2014, thereby preventing undesired movement of the scaffold 1000during use.

The scaffolds can be applied to a cartridge deck to form a staplecartridge assembly using any suitable method. For example, in someembodiments, the method can include heating a cartridge deck andpositioning a scaffold against a surface of the cartridge deck. Thescaffold can include first and second type of fibers in which the firsttype of fibers are predominately present. As used herein, “predominatelypresent” when used to describe the amount of particular fibers in alayer means an amount that is greater than 50% of the total amountfibers within that layer. The first type of fibers can have a firstglass transition temperature and the second type of fibers can have asecond glass transition temperature that is less than the first glasstransition temperature. The cartridge deck can be heated to atemperature of at least the second glass transitions temperature. Themethod can also include cooling the cartridge deck and scaffold appliedthereto to a temperature that is less than the second glass transitiontemperature.

The scaffold can include first and second knitted layers each having thefirst and second types of fibers and a support layer disposed betweenthe first and second knitted layers. In such instance, the positioningof the scaffold against the surface of the cartridge deck can includeplacing the first knitted layer against the surface and applying forceto the scaffold such that the first knitted layer bonds and conforms toa shape of the surface. The support layer can be formed of the secondtype of fibers.

The instruments disclosed herein can be designed to be disposed of aftera single use, or they can be designed to be used multiple times. Ineither case, however, the instrument can be reconditioned for reuseafter at least one use. Reconditioning can include any combination ofthe steps of disassembly of the instrument, followed by cleaning orreplacement of particular pieces and subsequent reassembly. Inparticular, the instrument can be disassembled, and any number of theparticular pieces or parts of the instrument can be selectively replacedor removed in any combination. Upon cleaning and/or replacement ofparticular parts, the instrument can be reassembled for subsequent useeither at a reconditioning facility, or by a surgical team immediatelyprior to a surgical procedure. Those skilled in the art will appreciatethat reconditioning of an instrument can utilize a variety of techniquesfor disassembly, cleaning/replacement, and reassembly. Use of suchtechniques, and the resulting reconditioned instrument, are all withinthe scope of the present application.

The present teachings may be further understood with reference to thefollowing non-limiting examples.

EXAMPLES Example 1: Manufacturing of a Scaffold

A sample having two knitted layers and a support layer positionedtherebetween was prepared. The two knitted layers were each formed ofVicryl fibers (multifilament fibers of Vicryl) and the support layer wasformed of Polydioxanone (PDS) fibers (monofilament fibers of PDS),details of which are provided in Table 1 below.

TABLE 1 Vicryl and Polydioxanone Fiber Information Fiber Diameter TenElongation Fiber (mils) (lbf) (%) 7-0 PDS, dyed 3.18 0.67 38.28 2 ply,28 denier Vicryl, natural 1.17 0.58 20.34

The sample was warp knit using a 16 gauge double needle bar Raschelknitting machine with a six guide bar (GB) construction. Each guide barwas individually controlled using a pattern chain, the patterns forwhich can be found in Table 2 below. PDS was used in the support layerand Vicryl was used for the knitted layers.

TABLE 2 Pattern Chain Guide Fiber Bars Guide Bar Movement Threading Used1 1-0; 0-0/1-2; 2-2/2-3; 3-3/2-1; 1-1// Fully Vicryl 2 2-3; 3-3/2-1;1-1/1-0; 0-0/1-2; 2-2// Threaded Vicryl 3 (1-0; 2-3) X 4// PDS 4 (2-3;1-0) X 4// PDS 5 2-2; 2-3/3-3; 2-1/1-1; 1-0/0-0; 1-2// Vicryl 6 1-1;1-0/0-0; 1-2/2-2; 2-3/3-3; 2-1// Vicryl

Approximately 6.4 yards of 5 inch wide sample was produced. The samplewas scoured with isopropyl alcohol. The sample was placed on a roll,sealed in a nitrogen purged foil bag, and kept under nitrogen flow untilfurther processing.

An approximate 5 inch×5 inch segment of the sample was then annealedusing cycle conditions as described in Table 3.

TABLE 3 Cycle Conditions N₂ Purge Ramp Up Annealing Cool Down Hours/Minutes/ Hours/ Minutes/ Temperature Temperature Speed TemperatureTemperature (° C.) (° C.) (° C./min) (° C.) (° C.) 1/30 90/85 0.94/16/85 60/30

The annealed sample was then cut to produce approximately 5 mm×10 mmsample scaffolds. One of the scaffold samples was examined by opticalmicroscopy (OM) and SEM. Various OM images of the sample scaffold isshown in FIGS. 8A-8C, and a cross-sectional SEM image of the scaffoldsample is shown in FIG. 9.

Example 2: Cellular Ingrowth and Limited Inflammation

Sample scaffolds as prepared in Example 1 were subcutaneously implantedfor up to 90 days into rabbits injected with a hematoxylin and eosinstain (H&E) stain. Histopathology images of an implanted scaffoldremoved at 60 days is illustrated in FIGS. 10A-10B and an implantedscaffold removed at 90 days is illustrated in FIGS. 11A-11B. The whiteovals/circles shown in these images are fibers of the scaffold cuteither perpendicular or slightly off. As shown, the black boxesillustrate some of the portions of the scaffold in which tissue ingrowthoccurred during implantation. Additionally, the arrows in FIGS. 10B and11B point to inflammatory areas around the fibers, which are indicativeof the inflammation phase of healing.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety. Any patent, publication, orinformation, in whole or in part, that is said to be incorporated byreference herein is incorporated herein only to the extent that theincorporated material does not conflict with existing definitions,statements, or other disclosure material set forth in this document. Assuch the disclosure as explicitly set forth herein supersedes anyconflicting material incorporated herein by reference.

What is claimed is:
 1. A method for manufacturing a scaffold for use ina surgical staple cartridge, the method comprising: forming a firstknitted layer that comprises fibers of a first polymer, the firstknitted layer being configured to mate with a cartridge deck; forming asecond knitted layer that comprises the first polymer fibers; andinterknitting spacer fibers with the first and second knitted layers soas to connect the first and second knitted layers together in a spacedparallel relation, the spacer fibers being formed of only a secondpolymer that is different than the first polymer, wherein the spacerfibers are integrated with and extending between the first and secondknitted layers, wherein the first polymer fibers have a diameter that isdifferent than a diameter of the second polymer fibers, and wherein thefirst polymer fibers have a first glass transition temperature and thesecond polymer fibers have a second glass transition temperature that isless than the first glass transition temperature.
 2. The method of claim1, wherein the first polymer fibers are multifilament fibers and thesecond polymer fibers are monofilament fibers.
 3. The method of claim 1,wherein the step of interknitting the spacer fibers with the first andsecond knitted layers forms a support layer therebetween.
 4. The methodof claim 3, wherein openings are present in the first and second knittedlayers and voids are present in the support layer, with the voids beinglarger than the openings.
 5. The method of claim 1, wherein theformation of the first knitted layer comprises knitting the firstpolymer fibers according to a predetermined pattern.
 6. The method ofclaim 1, wherein the first knitted layer has openings that each have asize that is less than about ¼ of a width of a crown of a staple.
 7. Themethod of claim 1, wherein the first polymer fibers are configured todegrade at a first rate and the second polymer fibers are configured todegrade at a second rate that is different than the first rate.
 8. Themethod of claim 1, wherein the first knitted layer further comprisesfibers of a third polymer, and wherein the formation of the firstknitted layer comprises knitting the first and third polymer fibersaccording to a predetermined pattern.
 9. The method of claim 8, whereinthe third polymer fibers are configured to degrade at a faster rate thana rate of degradation of the first polymer fibers.
 10. The method ofclaim 8, wherein the third polymer fibers are configured to degrade at afaster rate than a rate of degradation of the second polymer fibers. 11.The method of claim 1, wherein the formation of the second knitted layercomprises knitting the first polymer fibers according to a predeterminedpattern.
 12. The method of claim 1, wherein the second knitted layerfurther comprises fibers of a third polymer, and wherein the formationof the second knitted layer comprises knitting the first and thirdpolymer fibers according to a predetermined pattern.
 13. The method ofclaim 1, further comprising annealing the first and second knittedlayers interknitted with the spacer fibers.
 14. The method of claim 1,wherein the first polymer fibers have a first glass transitiontemperature and the second polymer fibers have a second glass transitiontemperature that is less than the first glass transition temperature.15. A method for manufacturing a scaffold for use in a surgical staplecartridge, the method comprising: forming a first knitted layer thatcomprises fibers of a first polymer, the first knitted layer beingconfigured to mate with a cartridge deck; forming a second knitted layerthat comprises the first polymer fibers; and interknitting spacer fiberswith the first and second knitted layers so as to connect the first andsecond knitted layers together in a spaced parallel relation, the spacerfibers being formed of only a second polymer that is different than thefirst polymer, wherein the spacer fibers are integrated with andextending between the first and second knitted layers, wherein the firstpolymer fibers have a first glass transition temperature and the secondpolymer fibers have a second glass transition temperature that is lessthan the first glass transition temperature.
 16. The method of claim 15,wherein the first polymer fibers are multifilament fibers and the secondpolymer fibers are monofilament fibers.
 17. The method of claim 15,wherein the step of interknitting the spacer fibers with the first andsecond knitted layers forms a support layer therebetween.
 18. The methodof claim 17, wherein openings are present in the first and secondknitted layers and voids are present in the support layer, with thevoids being larger than the openings.
 19. The method of claim 15,wherein the first knitted layer has openings that each have a size thatis less than about ¼ of a width of a crown of a staple.
 20. The methodof claim 15, wherein at least one of the first knitted layer and thesecond knitted layer further comprises fibers of a third polymer. 21.The method of claim 20, wherein the third polymer fibers are configuredto degrade at a faster rate than a rate of degradation of at least oneof the first polymer fibers and the second polymer fibers.